A little confused about my BMR..

Hey there, I'm a 16 year old 5'0 and 120 lbs. I've gained about 10 lbs during a month's worth of bad habit eating and sedentary lifestyle. All I want to do is get rid of the excess fat on my belly that had formed from the murderous month x_x
I'm just a little confused on how many calories I should be consuming in order to lose with a 500 calorie deficit. I limited myself to eat 1500-1800 calories and am exercising 80 mins on treadmill and 15 mins of rope skipping. I plugged myself into moderate and the BMI graph says I need 2250 calories. My question is in order to lose weight, am I supposed to eat 2250 calories or subtract 500 from that making me eat around 1750 calories? I don't know if the number they give me is the amount I need for my body to thrive or..something else? Please, and thanks. [:

I base myself using this: http://www.bcm.edu/cnrc/bodycomp/bmiz2.html

The number they give is to maintain. You'd want to be eating 1750 calories to lose a pound a week.

We have close to the same stats! I'm 4'11" and 125 lbs - I used to be 120 and was able to drop to 112 over the summer but first semester at college made me gain it back and then some. What's your goal weight? I'm looking to be 105

My original goal was 100 lbs when I was 110 lbs back a few months ago and the lowest I got was 103 lbs. That didn't last very long.. =/
My goal weight now is at least back to 110, if I accomplish that I probably would want to get down to 105 as well :]
We should buddy, maybe give each other some encouragement whenever needed.